java socket 模拟im 即时通讯
自己想了一下怎么实现,就写了,没有深究是否合理.更多处理没有写下去,例如收件人不在线,应该保存在数据库,等下一次连接的时候刷新map,再把数据发送过去,图片发送也没有做,也没有用json格式
socket很奇怪,我用客户端连接上了服务器,没有发送消息的情况下,断开电脑网络,是不会出现问题,然后在把电脑网络连接上,通讯依然正常,正常断开也不出问题,但是用idea直接按stop键,那么服务端就会出问题了,读取事件会一直为true,造成死循环,消耗CPU,所以必须要判断一下客户端连接是否断开了
只需要把客户端代码启动几个,修改一些userName以及收件人,就可以测试,实现类似QQ微信即时通讯,聊天功能
服务端代码
package serversocketchannel;import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.concurrent.ConcurrentHashMap;
/**
*
* @author ZhenWeiLai
*
*/
public class ServerSocketChannelNonBlocking {
private static ServerSocketChannel serverSocketChannel = null;
private static Charset charset = Charset.forName("GBK");//设置编码集,用于编码,解码
private static Selector selector = null;
//保存客户端的map
private static final ConcurrentHashMap<String,SocketChannel> clientSockets = new ConcurrentHashMap<>();
static{
try {
serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.socket().setReuseAddress(true);
serverSocketChannel.socket().bind(new InetSocketAddress(8000));
serverSocketChannel.configureBlocking(false);//设置为非阻塞
selector = Selector.open();//实例化一个选择器
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
service();
}
private static void service(){
SocketChannel clientChannel = null;
SelectionKey selectionKey = null;
SocketChannel targetChannel = null;
try {
serverSocketChannel.register(selector,SelectionKey.OP_ACCEPT);//服务端监听连接
while(true){
selector.select();//阻塞至有新的连接就开始处理
Iterator<SelectionKey> selectionKeys = selector.selectedKeys().iterator();
while(selectionKeys.hasNext()){
selectionKey = selectionKeys.next();
if(selectionKey.isAcceptable()){//如果事件是连接事件
ServerSocketChannel serverChannel = (ServerSocketChannel)selectionKey.channel();//获取事件绑定的channel
clientChannel = serverChannel.accept();//连接获取带客户端信息的socketChannel
clientChannel.configureBlocking(false);//客户设置为非阻塞,因为非阻塞才支持选择器.避免盲等浪费资源
ByteBuffer byteBuffer = ByteBuffer.allocate(1024);//作为每一个客户端的附件缓冲器
/**
* 只监听读事件,这里千万别监听写事件,因为只要连接有效,那么写事件会一直为true,导致死循环,很耗资源
* 可以跟serverSocket用同一个选择器,因为绑定的channel不同
*/
clientChannel.register(selector,SelectionKey.OP_READ,byteBuffer);
}else if(selectionKey.isReadable()){//只要有客户端写入,那么就可以处理
//获取客户端附件,也就是写入的数据
ByteBuffer byteBuffer = (ByteBuffer)selectionKey.attachment();
//从selectionKey获取客户端的channel
SocketChannel socketChannel = (SocketChannel)selectionKey.channel();
//把附件读出,解码为字符串
String msg = read(socketChannel,byteBuffer);
//这里用了->分割收件人,->后面跟着的字符串是收件人
if(msg.indexOf("->")!=-1){
//内容
String content = msg.substring(0,msg.lastIndexOf("->"));
//从map里获取收件人的socket
targetChannel = clientSockets.get(msg.substring(msg.lastIndexOf("->")+2));
//实例化一个缓冲区,用来写出到收件人的socketChannel
ByteBuffer temp = ByteBuffer.allocate(1024);
temp.put(charset.encode(content));
//写出
handleWrite(targetChannel,temp);
}else{
//如果内容没有收件人,那么视为第一次连接,客户端发过来的userName,作为KEY存入MAP
clientSockets.put(msg,socketChannel);
}
}
selectionKeys.remove();
}
}
} catch (IOException e) {
try {
if(selectionKey!=null)selectionKey.cancel();
if(clientChannel!=null){
clientChannel.shutdownInput();
clientChannel.shutdownOutput();
clientChannel.close();
}
if(targetChannel!=null){
targetChannel.shutdownInput();
targetChannel.shutdownOutput();
targetChannel.close();
}
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
e.printStackTrace();
}
}
private static String read(SocketChannel socketChannel,ByteBuffer byteBuffer){
//重置position limit为写入做准备
byteBuffer.clear();
try {
int flag =socketChannel.read(byteBuffer);
//判断客户端是否断开连接
if(flag==-1){
//如果客户端无故断开,一定要关闭,否则读取事件一直为true造成死循环,非常耗资源
socketChannel.close();
}
} catch (IOException e) {
try {
socketChannel.close();
} catch (IOException e1) {
e1.printStackTrace();
}
e.printStackTrace();
}
//position =0 limit等于有效下标,为写出做准备
byteBuffer.flip();
return charset.decode(byteBuffer).toString();
}
//写出
private static void handleWrite(SocketChannel socketChannel,ByteBuffer byteBuffer){
synchronized (byteBuffer) {
byteBuffer.flip();
try {
socketChannel.write(byteBuffer);
} catch (IOException e) {
try {
socketChannel.close();
} catch (IOException e1) {
e1.printStackTrace();
}
e.printStackTrace();
}
}
}
}
客户端代码
package socketchannel;import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.util.Iterator;
/**
* Created by lzw on 17-2-28.
*/
public class SocketChannelNonBlockingClient {
private static Charset charset = Charset.forName("GBK");
private static ByteBuffer receiveBuffer = ByteBuffer.allocate(10240);
private static ByteBuffer sendBuffer = ByteBuffer.allocate(10240);
private static SocketChannel socketChannel = null;
private static Selector selector = null;
private static String userName = "client1";//客户端名
private static String targetName = "client2";//收件人名
public static void main(String[] args) {
try {
socketChannel = SocketChannel.open();
//连接到服务端
SocketAddress socketAddress = new InetSocketAddress("19.95.103.112",8000);
selector = Selector.open();//实例化一个选择器
socketChannel.configureBlocking(false);//设置为非阻塞
//先监听一个连接事件
socketChannel.register(selector,SelectionKey.OP_CONNECT);
//连接
socketChannel.connect(socketAddress);
//jdk 1.8的lambda表达式，用一个线程监控控制台输入
new Thread(()->{
try {
receiveFromUser();
} catch (IOException e) {
e.printStackTrace();
}
}).start();
talk();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private static void talk(){
try {
while(true){
selector.select();//阻塞直到连接事件
Iterator<SelectionKey> readyKeys = selector.selectedKeys().iterator();
while(readyKeys.hasNext()){
SelectionKey key =readyKeys.next();
if(key.isConnectable()){
//非阻塞的情况下可能没有连接完成，这里调用finishConnect阻塞至连接完成
socketChannel.finishConnect();
//连接完成以后，先发送自己的userName以便保存在服务端的客户端map里面
synchronized (sendBuffer){
SocketChannel socketChannel1 = (SocketChannel)key.channel();
sendBuffer.clear();
sendBuffer.put(charset.encode(userName));
send(socketChannel1);
socketChannel.register(selector,SelectionKey.OP_READ);//仅监听一个读取事件
}
}else if(key.isReadable()){
//处理读事件
receive(key);
}
readyKeys.remove();
}
}
} catch (ClosedChannelException e) {
try {
socketChannel.close();
} catch (IOException e1) {
e1.printStackTrace();
}
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/**
* 从控制台获取用户输入
* @throws IOException
*/
private static void receiveFromUser() throws IOException{
//阻塞直到控制台有输入
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
for(String msg = br.readLine();msg!=null&&!msg.equals("bye");msg = br.readLine()){
//同步锁避免线程竞争
synchronized (sendBuffer) {
sendBuffer.clear();
//编码
sendBuffer.put(charset.encode(msg));
//分割副
sendBuffer.put(charset.encode("->"));
//目标名
sendBuffer.put(charset.encode(targetName));
send(socketChannel);
}
}
}
/**
* 接收服务端的数据
* @param key
*/
private static void receive(SelectionKey key) throws IOException {
//获取服务端的channel
SocketChannel channel = (SocketChannel) key.channel();
//为写入缓冲器做准备position=0,limit=capacity
receiveBuffer.clear();
//从服务端的channel把数据读入缓冲器
channel.read(receiveBuffer);
//position=0,limit=有效下标最后一位
receiveBuffer.flip();
//解码
String msg = charset.decode(receiveBuffer).toString();
//输出到控制台
System.out.println(msg);
}
/**
* 发送到服务端
*/
private static void send(SocketChannel sendChannel) throws IOException {
if(sendBuffer.remaining()!=0){
synchronized (sendBuffer){
sendBuffer.flip();
sendChannel.write(sendBuffer);
}
}
}
}
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